J7ournal ofNeurology, Neurosurgery, and Psychiatry 1994;57:89-93

Unilateral spatial neglect due to right frontal lobehaematoma

Shinichiro Maeshima, Kazuyoshi Funahashi, Mitsuhiro Ogura, Toru Itakura,Norihiko Komai

AbstractTwo patients with unilateral spatialneglect caused by right frontal lobelesions underwent cerebral blood flowstudies. A 54-year-old, right-handedwoman developed left hemiplegia andfrontal lobe neglect associated with cere-bral haemorrhage after surgical excisionof a frontal tumour. A 66-year-old, right-handed woman developed a haemor-rhage in the right frontal lobe caused byrupture of an aneurysm. This was fol-lowed by left hemiplegia and frontal lobeneglect. In both cases, '23I-iodoampheta-mine single photon emission CT dis-closed a reduction in regional cerebralblood flow localised along the circumfer-ence of the haematoma in the frontallobe, but did not reveal any lesions in theparieto-occipital junction. These findingssuggest that, in these two cases, thefrontal lobe neglect was caused by lesionsconfined to the frontal lobe.

(J Neurol Neurosurg Psychiatry 1994;57:89-93)

Unilateral spatial neglect is a symptomwherein the patient disregards objects existing

Department ofNeurological Surgery,Wakayama MedicalCollege, Wakayama,JapanS MaeshimaK FunahashiM OguraT ItakuraN KomaiCorrespondence to:Dr Shinichiro Maeshima,Departmnent of NeurologicalSurgery, Wakayama MedicalCollege, 27 Nanaban-cho,Wakayama 640, Japan.Received 17 August 1992and in revised form9 March 1993.Accepted 31 March 1993

in the outer half. Lesions in the parieto-occipital junction in the right hemispherehave generally been considered responsiblefor this symptom.1 2 Unilateral spatial neglectis also thought to reflect a disturbance in thespatial distribution of directed attention.3There have been reports of this symptomoccurring in association with lesions in theoccipital and frontal lobes, subcortical lesionsinvolving the thalamus or putamen, and lefthemispheric lesions.4" The phenomenon ofunilateral spatial neglect reflects deficits in atleast one of the centres responsible for spatialprocessing, selective attention, mental repre-sentation, awareness, or premotor planning.The responsible lesion and mechanism arestill controversial. We report on two cases offrontal lobe neglect associated with rightfrontal lobe damage. We discuss the cere-brovascular kinetics and lesions responsible inthese cases.

Case reportsCASE 1A 54-year-old, right-handed woman hadheadache and vomiting in the morning of July13, 1990. Her precontrast CT scan on July16 showed a slight abnormality. She was

Figure 1 TTon admissson revealed an enhanced tumour in the rightfrontal lobe (top row). CTon the third day aftersurgery revealed a haematoma confined to the rightfrontal lobe (bottom row).

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Figure 2 Neglect of theleft side was seen in someneuropsychological tasks.

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referred to our hospital for close examinationon July 19. On admission she was alert, ori-ented, and appropriately motivated. Cranialnerves were intact. There were neither sen-sory nor motor deficits. A CT scan revealed acontrast enhancing tumour in the rightfrontal lobe (fig 1, top); cerebral angiographyshowed tumour stain and vessels feedingfrom the right middle meningial artery. Thesefindings supported a diagnosis of a convexitymeningioma in the right frontal lobe. OnAugust 20, frontal craniotomy and totalmeningioma excision were performed undergeneral anaesthesia. After the operation, thepatient regained consciousness and was with-out sensory or motor deficit. On the thirdpostoperative day, however, a disturbance inconsciousness and a left hemiplegia werenoted. A CT scan revealed a high densityarea confined to the right frontal lobe (fig 1,bottom). A postoperative intracerebral haema-toma was surgically removed on August 23.The day after the evacuation, she becamealert and oriented. She had full visual fieldsby a confrontational testing, normal extra-ocular movements, left-sided facial palsy anda severe left hemiparesis. Perception of pin,touch, vibration, proprioception, grapha-esthesia, and stereognosis were normal.

Neuropsychological examinationOn September 2, the 10th postoperative day,neurological examinations were performed.Dementia was not observed and Hasegawa'ssimple intelligence test scale was 270/32 5(subnormal). Digit span was performed suc-cessfully for up to seven digits, and word flu-ency (animal names) was 13 per minute.Aphasia was not seen and there were noabnormalities in reading vertically written let-ters and words, or in writing her own name.Neglect of the left side was seen in line bisec-tion, line cancellation, figure copying tests,and in describing scenic pictures (fig 2).

Figure 3'23I-iodoamphetaminesingle photon emission CTwas performed in thesecond week after surgery.It showed a decrease inregional cerebral bloodflowin the circumference of thehaematoma in thefrontallobe in early images (toprow) and a redistributionphenomenon in delayedimages (bottom row).

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Unilateral spatial neglect due to rightfrontal lobe haematoma

Figure 4 CT scan on theday after the onset ofheadache and vomiting inpatient 2 disclosedhaemorrhage in the rightfrontal lobe (top row).Postoperative CT revealeda low density area in thelateral side of the rightfrontal lobe (bottom row).

There was left sided extinction in the visual,auditory, and tactile modalities on bilateral,simultaneous stimulation. Ideomotor apraxia,ideational apraxia, or anosognosia were notobserved.

Clinical courseA 1231-iodoamphetamine single photon emis-sion CT (SPECT) study was performed inthe second postoperative week. It showed adecrease in the regional cerebral blood flowalong the circumference of the haematoma inthe frontal lobe in early images and a redistri-bution phenomenon in the delayed images(fig 3). A Wechsler adult intelligence scaleverbal IQ was 92. Several neuropsychological

examinations were performed on September30 (the 38th postoperative day), and therewas some improvement in the left-sidedneglect. Abnormalities were still noted in linebisection, line cancellation tests, and extinc-tion in all sensory modalities on bilateral,simultaneous stimulation. Subsequently, left-side neglect gradually improved and disap-peared three months later. Repeat '23I-IMPSPECT showed that the reduced regionalcerebral blood flow in the frontal loberemained unchanged.

CASE 2A 66-year-old, right-handed woman had anattack of headache and vomiting on February 7,

Figure 5'23I-iodoamphetaminesingle photon emission CTin the third week aftersurgery showed a decreasein regional cerebral bloodflow in the circumference ofthe haematoma in thefrontal lobe in early images(top row) and aredistribution phenomenonin delayed images (bottomrow).

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Figure 6 Neglect of theleft side was seen in someneuropsychological tasks.

Neuropsychological examinationOn April 6, the second postoperative week,neurological examinations were carried out.The patient had mild disorientation andmemory disturbance but no general dementiaor aphasia. Digit span was performed suc-cessfully up to six digits, and word fluency(animal names) was two per minute. Therewere no abnormalities in reading verticallywritten letters and words or in writing herown name. Left-sided neglect, however, wasobserved in line bisection, line cancellation,and figure copying tests, and in describingscenic pictures (fig 6). There was left-sidedextinction in the visual, auditory, and tactilemodalities on bilateral, simultaneous stimula-tion. Ideomotor apraxia, ideational apraxia,or anosognosia were not observed.

Clinical coursePostoperative CT revealed a low density areain the lateral aspect of the right frontal lobe(fig 4, bottom). A 123I-IMP SPECT scan inthe third postoperative week showed adecrease in regional cerebral blood flow alongthe circumference of the haematoma in thefrontal lobe in early images and a redistribu-tion phenomenon in the delayed images (fig5). In the fourth postoperative week, thepatient was referred to another hospital forrehabilitation.

1991. The headache disappeared in a fewdays, but she remained resting at homebecause of general malaise. On February 19,she suffered a second attack of headache andvomiting and noticed weakness of her leftarm and leg. The next day a CT scan dis-closed a haemorrhage in the right frontal lobe(fig 4, top). On March 11, when she was

referred to our hospital, she was alert and ori-ented. She had left-sided facial palsy andmoderate left hemiparesis but no visual fielddefect by confrontational testing. Perceptionof pin, touch, vibration, proprioception,graphaesthesia, and stereognosis were nor-

mal. Cerebral angiography revealed an

aneurysm in the distal part of the left anteriorcerebral artery. On March 22, neck clippingand total removal of the haematoma were

successfully performed with an interhemi-spheric approach. Neurological symptoms,such as hemiplegia, did not obviouslyimprove.

DiscussionHeilman et al 4 reported six cases with unilat-eral spatial neglect caused by lesions in thefrontal lobe, naming the syndrome "frontallobe neglect". However, their study was madebefore the introduction of the CT scan, so

there may be ambiguity in the identificationof lesion sites, except in the one autopsiedcase. Damasio et al5 reported five cases offrontal lobe neglect; two of them had lesionsin the basal ganglia and the other three in theleft frontal lobe. Employing CT, Kubo6 inves-tigated the causative lesions in 28 cases ofunilateral spatial neglect, and found that noneof these lesions were confined to the frontallobe. Valler et al 7 reported that lesions con-

fined to the frontal lobe were detected in onlyone patient with unilateral spatial neglect, of1 10 cases with right hemispheric stroke.Therefore, it may well be that cases of frontallobe neglect caused by lesions confined to thefrontal lobe are rare. Imamura et a18 havestated some conditions for unilateral spatialneglect associated with frontal lobe lesions:firstly, the lesion extends to the basal ganglia;secondly the lesion involves the occipital lobeas well as the frontal lobe; or thirdly, the sub-cortical lesion in the frontal lobe is extensive.In both the present cases, an extensive sub-cortical lesion was noted in the frontal lobebut did not involve the parieto-occipital lobe,and was not easily detectable in the basalganglia.

Concerning the mechanism of frontal lobeneglect caused by subcortical lesions,Heilman et all have hypothesised that pres-sure on the surrounding tissues by the lesion

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produces a disconnection of nerve fibres pro-jecting to the cortex, or damages corticalfunction at the subcortical level. Valler et al9examined functional lesions in two patientswith unilateral spatial neglect and subcorticalvascular lesions using SPECT, and suggestedthat the right frontotemporoparietal cortexcould be the site of the lesion responsible. Wehave examined functional lesions in thalamicneglect using xenon-enhanced CT andhypothesise that the origin of the disturbedcortical function can be found in the parieto-occipital lobe.'0 In the present cases, however,we did not find a reduction in cerebral bloodflow in the parieto-occipital junction, even atthe time when frontal lobe neglect was beingobserved. Therefore, neglect would appear tooccur in association with a single lesion con-fined to the frontal lobe. In case 1, whenfrontal lobe neglect had already disappeared,SPECT showed no improvement in thereduction of cerebral blood flow, but rather aredistribution phenomenon in the delayedimage. This phenomenon seemed to be dueto activation of the remaining cortex.

Heilman et al 1 4emphasised the participa-tion of Brodmann's areas eight, nine and 46,including a dorsolateral part of the frontallobe, in frontal lobe neglect. They have sug-gested that this condition could occurbecause of an insult to the connecting fibres,including fibres conveying visual, somatic,and auditory information, between the frontalcortex and the inferior parietal lobule. Theyhave also reported that the supplementarymotor area and cingulate gyrus, both ofwhich are connected to a dorsolateral portionof the frontal lobe, are responsible in frontallobe neglect.4 Mesulam et al 3 11 suggested thatfour cerebral regions-the posterior, parietal,frontal, and reticular components-providean integrated network for the modulation ofattention within extrapersonal space. Eachcomponent region has a unique functionalrole that reflects its profile of anatomical con-nectivity, and each gives rise to a differentclinical type of unilateral spatial neglect whendamaged. Lesions in only one component ofthis network yield parietal unilateral spatialneglect, whereas those that encompass all thecomponents result in profound deficits thattranscend the mass effect of the larger lesion.Illustratively, it is thought that a right frontalinjury causes only left-sided, exploratorymotor hemispatial neglect.'2 From the presentcases, it appears that an extensive subcorticallesion in the frontal lobe involved the con-necting fibres between the frontal cortex andthe inferior parietal lobule, resulting in frontallobe neglect. The study of attention andmovement in macaque monkey by Rizzolatti

et al 3reported that area six caused neglect insomatosensory and visual modalities but areaeight did not cause somatosensory deficit.

In this study, we could not determinewhether the patients had exploratory motorhemispatial neglect, because patients werenot challenged with an exploratory motortask. But unilateral spatial neglect in thesetwo patients was most obvious during thecancellation, figure copying, and picturescene tests. Additionally, there was left-sidedextinction in the visual, auditory, and tactilemodalities on bilateral simultaneous stimula-tion. The network for directed attention is soheavily interconnected, and the lesion in thefrontal lobe was so large, that the unilateralspatial neglect in the two patients appears tobe multifactorial. There was no qualitativedifference in the performance of the twowomen, but the unilateral spatial neglect inpatient 1 was more severe than that of patient2. It seems that this difference in severity wasdependent on the volume of the haematomain the right frontal lobe.

In our two cases of frontal lobe neglectcaused by lesions confined to the right frontallobe, the lesion did not involve the parieto-occipital lobe, even on cerebral blood flowstudies. This finding suggests that frontallobe neglect in these two cases was caused bya mechanism that does not involve theparieto-occipital lobe or thalamus.

1 Heilman KM, Valenstein E, Watson RT. Localization ofneglect In Kertesz A, ed. Lcazaion in oly.New York: Acadc Press, 1983:471-92.

2 Kubo K Localition of unilateral spial neglect. HigherBrain Funa Res 1989;9:106-1 1.

3 Mesulam MM, Attention, confusional states, and neglect.In Mesulam MM, ed. Pinis f behavioral neurology.Philadelphia: FA Davis, 1985:125-68.

4 Heilmann MH, Valenstein E. Frontal lobe neglect in man.Neurology 1971;22:660-4.

5 Damasio AR, Damasio H, Chui HC. Neglect followingdamage to frontal lobe or basal ganglia. Neuropsychologia1980;l8:123-32.

6 Kubo K Unilateral spatial neglect. Adv Neuro (Jpm)1980;24:598-609.

7 Vallar G. Perani D. The anatomy of unilateral neglectafter right hemisphere stroke lesions. A clinical/CT-scancorrelation study in man. Neuropsychologia 1986;17:493-501.

8 Imamura Y, Uemura K Unilateral spatial neglect follow-ing damage to right frontal lobe. Higher Brain Funct ResOJpn) 1989;9:211-8.

9 Vallar G, Perani D, Cappa SF, et al. Recovery from apha-sia and neglect after subcortical stroke: neuropsycholog-ical and cerebral perfusion study. J Neurol NeurosurgPsychiatry 1988;51:1269-76.

10 Maeshima S, Hyoutani G, Terada T, Nakamura Y,Yokote H, Komai N, et al. Effect of thalamic neglect onactivities of daily living. Sogo Rehabil 1990;18:445-50.

11 Daffner KR, Ahern GL, Weintraub S, Mesulam MM.Dissociated neglect behavior following sequentialstrokes in the right hemisphere. Ann Neurol 1990;28:97-101.

12 liu GT, Bolton AK, Price BH, Weintraub S. Dissociatedperceptual-sensory and exploratory-motor neglect.Neurol Neurosurg Psychiatry 1992;55:701-6.

13 Rizzolatti G, Matelli M, Pavesi G. Deficits in attentionand movement following the removal of postarcuate(area 6) and prearcuate (area 8) cortex in macaquemonkeys. Brain 1983;106:655-73.

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